RGB Strip PWM Output delayed and stuttering

i have a problem addressing an 1m rgb strip using an Arduino Duemilanove.

I followed the rgb strip tutorial on this site ( RGB LED strip tutorial ) using 3 PWM Pins (1 for each channel) with 3 N-channel MOSFETs (STP16NF06) and an exteral 12V Power supply.

I’m using the Firmata firmware and the maxuino max4live patch to speak to the arduino. Basically addressing the strip works fine, but just one pwm pin at the same time. If i’m addressing two or three pwm pins simultaneous the output begins to stutter and is clearly delayed. It seems like the arduino can’t handle all the pwm data at the same time. I’ve already done some research but just can’t figure out exactly where’s the weak point.

I would be very very thankful to get some tips!!

Arduino can control all of its PWM outputs at the same time without stuttering.

If you post your sketch then we can help you find the problem.

thanks for the fast reply!

Since I'm controlling the arduino with max/msp I'm using the standard firmata sketch in combination with the maxuino max/msp patch! Do you need further information?

Thanks in advance!

Well you don't give us much to go on do you. It would be better if you try and isolate which end is giving you the trouble. While firmata is convenient for people who don't want to know what is going on it has the disadvantage that when anything goes wrong there is not much you can do about it.

I would try and look at the output of your max patch in a terminal and see if it is sending stuttering information.


ok i'll give it a try and will report afterwards.

ok, somehow i figured it out. Checking the Data output from max/msp to the arduino everything ran smoothly. Apparently the bottleneck was softwarebased anywhere between ableton live and the maxuino max4life patch, maybe it has to do with converting all the midi data from live to pwm data, i don't know.

When i'm running some standalone max patches addressing the pwm pins via maxuino/firmata everything just works fine, so it's no hardware issue.

thanks for the tip!!